WO2011045927A1

WO2011045927A1 - Encoding device, decoding device and methods therefor

Info

Publication number: WO2011045927A1
Application number: PCT/JP2010/006088
Authority: WO
Inventors: 山梨智史
Original assignee: パナソニック株式会社
Priority date: 2009-10-14
Filing date: 2010-10-13
Publication date: 2011-04-21
Also published as: JPWO2011045927A1; US8949117B2; EP2490217A4; EP2490217A1; JP5544371B2; US20120203546A1

Abstract

Disclosed is an encoding device, wherein the energy information of a given layer is efficiently encoded using a scalable encoding method in which the band to be encoded is selected in each layer, and the quality of decoded signals can be enhanced. An encoding device (101) is equipped with: a second layer encoding unit (205) which selects from among a plurality of sub-bands, the frequency regions of which are divided, a first band to be quantized in a first layer differential spectrum as a first input signal, and generates a second layer encoded information included in which is the first band information of said band; a second layer decoding unit (206) which generates a first decoding signal by using the second layer encoded information; an adding unit (207) which generates a second layer differential spectrum as a second input signal by using the first input signal and the first decoding signal; and a third layer encoding unit (208) which generates a third layer encoded information included in which is a second band information obtained by selecting a second band to be quantized in the second input signal, and a gain (energy information) which was corrected by using the first band information and the second band information.

Description

Encoding device, decoding device and methods thereof

The present invention relates to an encoding device, a decoding device, and these methods used in a communication system that encodes and transmits a signal.

When transmitting voice / musical sound signals in packet communication systems typified by Internet communication or mobile communication systems, compression / coding techniques are often used to increase the transmission efficiency of voice / musical sound signals. In recent years, there has been an increasing need for a technique for encoding a voice / music signal of a wider band with high quality while simply encoding a voice / music signal at a low bit rate.

In response to such needs, various technologies for hierarchically integrating a plurality of encoding technologies have been developed. For example, in Non-Patent Document 1, a spectrum of a desired frequency band (MDCT (Modified Discrete Cosine Transform)) is obtained using TwinVQ (Transform Domain Weighted Interleave Vector Quantization) in which the basic structural unit is modularized. A method of hierarchically encoding (coefficients) is disclosed. By using the module in common and using it a plurality of times, a simple and highly flexible scalable encoding can be realized. In this method, the subbands to be encoded in each layer (layer) are basically configured in advance, but the subbands to be encoded in each layer (layer) according to the nature of the input signal. A configuration is also disclosed in which the position of is fluctuated within a predetermined band.

However, in the above Non-Patent Document 1, when a subband to be encoded is selected from a plurality of candidates in each layer (layer), consider whether the selected subband has already been encoded in a lower layer. Encoding is performed. Therefore, for example, when vector quantization is performed on energy information of subbands already selected in the lower layer, vector quantization is performed regardless of the magnitude of the residual energy of each subband, resulting in high coding performance. There is a problem that cannot be obtained.

An object of the present invention is to provide a code that can efficiently encode energy information of the current layer and improve the quality of a decoded signal in a scalable coding scheme that selects a band to be coded in each layer (layer). It is to provide an encoding device, a decoding device, and these methods.

One aspect of an encoding apparatus according to the present invention is an encoding apparatus having at least two encoding layers, which receives a first input signal in a frequency domain and has a plurality of subbands obtained by dividing the frequency domain. A first quantization target band of the first input signal is selected from among the first input signals in the first quantization target band, and includes first band information of the first quantization target band Generating first encoded information, generating a first decoded signal using the first encoded information, and generating a second input signal using the first input signal and the first decoded signal. A first layer encoding means, the second input signal and the first encoded information are input, a second quantization target band of the second input signal is selected from the plurality of subbands, and second While obtaining band information, the second quantization target band A gain of the second input signal is obtained, and the second input signal of the second quantization target band is encoded using the first encoded information, and the second band information and the gain are encoded. Second layer encoding means for generating second encoded information including gain encoded information obtained.

One aspect of a decoding apparatus according to the present invention is a decoding apparatus that receives and decodes information generated in an encoding apparatus having at least two encoding layers, the first layer code of the encoding apparatus The first encoded information including the first band information generated by selecting the first quantization target band of the first layer from the plurality of subbands obtained by dividing the frequency domain; Generated by selecting the second quantization target band of the second layer from the plurality of subbands obtained by encoding of the second layer of the encoding device using the first encoding information. The second encoded information including the second band information, and receiving means for receiving the information; and the first encoded information obtained from the information is input and included in the first encoded information Based on the first band information First layer decoding means for generating a first decoded signal for the set first quantization target band, the first encoded information and the second encoded information obtained from the information are input, and the second Secondly, a signal for the second quantization target band set based on the second band information included in the encoded information is corrected using the first encoded information and the second encoded information. Second layer decoding means for generating a decoded signal.

One aspect of an encoding method according to the present invention is an encoding method in which encoding is performed with at least two encoding layers, and a plurality of frequency domain first input signals are input and the frequency domain is divided. A first quantization target band of the first input signal is selected from the subbands, the first input signal of the first quantization target band is encoded, and the first band of the first quantization target band is encoded. First encoded information including information is generated, a first decoded signal is generated using the first encoded information, and a second input signal is generated using the first input signal and the first decoded signal. A first layer encoding step to be generated, the second input signal and the first encoding information are input, and a second quantization target band of the second input signal is selected from the plurality of subbands. To obtain the second band information and the second quantum A gain of the second input signal in the target band is obtained, and the second input signal in the second quantization target band is encoded using the first encoded information, and the second band information and the gain are calculated. A second layer encoding step for generating second encoded information including gain encoded information obtained by encoding.

One aspect of a decoding method according to the present invention is a decoding method for receiving and decoding information generated in an encoding device having at least two encoding layers, the first layer code of the encoding device The first encoded information including the first band information generated by selecting the first quantization target band of the first layer from the plurality of subbands obtained by dividing the frequency domain; Generated by selecting the second quantization target band of the second layer from the plurality of subbands obtained by encoding of the second layer of the encoding device using the first encoding information. The second encoded information including the second band information, a reception step for receiving the information, and the first encoded information obtained from the information is input and included in the first encoded information Based on the first band information A first layer decoding step for generating a first decoded signal for the first quantization target band that is set, and input the first encoded information and the second encoded information obtained from the information, A signal for the second quantization target band set based on the second band information included in the second encoded information is corrected using the first encoded information and the second encoded information, A second layer decoding step of generating two decoded signals.

According to the present invention, in a hierarchical coding (scalable coding) method in which a band to be coded is selected for each layer (layer), the current layer is based on a lower layer coding result (quantized band). By switching the encoding method of energy information in the quantization target band, energy information can be efficiently encoded, and as a result, the quality of the decoded signal can be improved.

The block diagram which shows the structure of the communication system which has the encoding apparatus and decoding apparatus which concern on one embodiment of this invention The block diagram which shows the main structures inside the encoding apparatus shown in FIG. The block diagram which shows the main structures inside the 2nd layer encoding part shown in FIG. The figure which shows the structure of the region which concerns on the said embodiment. The block diagram which shows the main structures inside the 2nd layer decoding part shown in FIG. The block diagram which shows the main structures inside the 3rd layer encoding part shown in FIG. The block diagram which shows the main structures inside the decoding apparatus shown in FIG. The block diagram which shows the main structures inside the 3rd layer decoding part shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that a speech encoding device and a speech decoding device will be described as examples of the encoding device and the decoding device according to the present invention.

(Embodiment)
FIG. 1 is a block diagram showing a configuration of a communication system having an encoding device and a decoding device according to an embodiment of the present invention. In FIG. 1, the communication system includes an encoding device 101 and a decoding device 103, and can communicate with each other via a transmission path 102. Note that both the encoding apparatus 101 and the decoding apparatus 103 are normally mounted and used in a base station apparatus or a communication terminal apparatus.

The encoding apparatus 101 divides the input signal into N samples (N is a natural number), and encodes each frame with N samples as one frame. Here, an input signal to be encoded is represented as x (n). n (n = 0,..., N−1) represents the (n + 1) th signal element in the input signal divided by N samples. The encoding apparatus 101 transmits encoded input information (hereinafter referred to as “encoding information”) to the decoding apparatus 103 via the transmission path 102.

The decoding device 103 receives the encoded information transmitted from the encoding device 101 via the transmission path 102, decodes it, and obtains an output signal.

FIG. 2 is a block diagram showing a main configuration inside the encoding apparatus 101 shown in FIG. As an example, the encoding apparatus 101 is a hierarchical encoding apparatus including three encoding hierarchies (layers). Here, the first layer, the second layer, and the third layer are referred to in order from the lowest bit rate.

The first layer encoding unit 201 generates the first layer encoded information by encoding the input signal using, for example, a CELP (Code Excited Linear Prediction) method audio encoding method. The first layer encoded information is output to first layer decoding section 202 and encoded information integration section 209.

First layer decoding section 202 decodes the first layer encoded information input from first layer encoding section 201 using, for example, a CELP speech decoding method, and converts the first layer decoded signal to The generated first layer decoded signal is output to adding section 203.

The adding unit 203 inverts the polarity of the first layer decoded signal and adds it to the input signal to calculate a difference signal between the input signal and the first layer decoded signal, and the obtained difference signal is used as the first layer. It outputs to the orthogonal transformation process part 204 as a difference signal.

The orthogonal transform processing unit 204 has a buffer buf1 (n) (n = 0,..., N−1) inside, and modifies the first layer differential signal x1 (n) by a modified discrete cosine transform (MDCT). ) To convert to a frequency domain parameter (frequency domain signal).

Next, the orthogonal transformation processing in the orthogonal transformation processing unit 204 will be described with respect to the calculation procedure and data output to the internal buffer.

First, the orthogonal transform processing unit 204 initializes the buffer buf1 (n) using “0” as an initial value according to the following equation (1).

Next, the orthogonal transform processing unit 204 performs a modified discrete cosine transform (MDCT) on the first layer difference signal x1 (n) according to the following equation (2), and the MDCT coefficient of the first layer difference signal x1 (n): X1 (k) is obtained (hereinafter referred to as “first layer difference spectrum”).

Here, k represents the index of each sample in one frame. The orthogonal transform processing unit 204 obtains x1 ′ (n), which is a vector obtained by combining the first layer differential signal x1 (n) and the buffer buf1 (n), using the following equation (3).

Next, the orthogonal transform processing unit 204 updates the buffer buf1 (n) using Expression (4).

Then, the orthogonal transform processing unit 204 outputs the first layer difference spectrum X1 (k) to the second layer encoding unit 205 and the adding unit 207.

The second layer encoding unit 205 generates the second layer encoded information using the first layer difference spectrum X1 (k) input from the orthogonal transform processing unit 204, and the generated second layer encoded information is Output to second layer decoding section 206, third layer encoding section 208, and encoded information integration section 209. Details of second layer encoding section 205 will be described later.

The second layer decoding unit 206 decodes the second layer encoded information input from the second layer encoding unit 205 and calculates a second layer decoded spectrum. Next, second layer decoding section 206 outputs the generated second layer decoded spectrum to addition section 207. Details of second layer decoding section 206 will be described later.

The adding unit 207 calculates the difference spectrum between the first layer difference spectrum and the second layer decoded spectrum by inverting the polarity of the second layer decoded spectrum and adding the result to the first layer difference spectrum. The difference spectrum is output to third layer encoding section 208 as the second layer difference spectrum.

Third layer encoding section 208 uses the second layer encoded information input from second layer encoding section 205 and the second layer differential spectrum input from adding section 207 to generate third layer encoded information. And the generated third layer encoded information is output to the encoded information integration section 209. Details of third layer encoding section 208 will be described later.

The encoding information integration unit 209 includes first layer encoding information input from the first layer encoding unit 201, second layer encoding information input from the second layer encoding unit 205, and third layer encoding. The third layer encoded information input from the encoding unit 208 is integrated. The encoded information integration unit 209 adds a transmission error code or the like to the integrated information source code, if necessary, and outputs this to the transmission path 102 as encoded information.

FIG. 3 is a block diagram showing the main configuration of second layer encoding section 205.

In this figure, the second layer encoding unit 205 includes a band selection unit 301, a shape encoding unit 302, a gain encoding unit 303, and a multiplexing unit 304.

The band selection unit 301 divides the first layer difference spectrum input from the orthogonal transform processing unit 204 into a plurality of subbands, selects a band to be quantized (quantization target band) from the plurality of subbands, Band information indicating the selected band is output to the shape encoding unit 302 and the multiplexing unit 304. Band selection section 301 also outputs the first layer difference spectrum to shape coding section 302. Note that the input of the first layer difference spectrum to the shape encoding unit 302 is directly input from the orthogonal transform processing unit 204 to the shape encoding unit 302 separately from the input from the orthogonal transform processing unit 204 to the band selection unit 301. You may make it. Details of the processing of the band selection unit 301 will be described later.

The shape encoding unit 302 uses the spectrum (MDCT coefficient) corresponding to the band indicated by the band information input from the band selection unit 301 among the first layer difference spectra input from the band selection unit 301. Encoding is performed to generate shape encoding information, and the generated shape encoding information is output to the multiplexing unit 304. Further, shape coding section 302 obtains an ideal gain (gain information) calculated at the time of shape coding, and outputs the obtained ideal gain to gain coding section 303. Details of the processing of the shape encoding unit 302 will be described later.

The ideal gain is input from the shape encoding unit 302 to the gain encoding unit 303. The gain encoding unit 303 quantizes the ideal gain input from the shape encoding unit 302 to obtain gain encoded information. Gain coding section 303 outputs gain coding information obtained to multiplexing section 304. Details of the processing of the gain encoding unit 303 will be described later.

The multiplexing unit 304 multiplexes the band information input from the band selection unit 301, the shape encoding information input from the shape encoding unit 302, and the gain encoding information input from the gain encoding unit 303. The resulting bitstream is output as second layer encoded information to second layer decoding section 206, third layer encoding section 208, and encoded information integration section 209.

The second layer encoding unit 205 having the above configuration performs the following operation.

The first layer difference spectrum X1 (k) is input from the orthogonal transform processing unit 204 to the band selection unit 301.

Band selection section 301 first divides first layer difference spectrum X1 (k) into a plurality of subbands. Here, a case will be described as an example where J (J is a natural number) subbands are evenly divided. Then, the band selection unit 301 selects L (L is a natural number) subbands among the J subbands, and obtains M (M is a natural number) types of subband groups. Hereinafter, this group of M types of subbands is referred to as a region.

FIG. 4 is a diagram illustrating a configuration of a region obtained by the band selection unit 301.

In this figure, the number of subbands is 17 (J = 17), the types of regions are 8 (M = 8), and each region is composed of 5 consecutive subbands (L = 5). Has been. Among them, for example, the region 4 includes subbands 6 to 10.

Next, the band selection unit 301 calculates the average energy E1 (m) of each of the M types of regions according to the following equation (5).

In this equation, j represents the index of each of the J subbands, and m represents the index of each of the M types of regions. S (m) indicates the minimum value among the indices of the L subbands constituting the region m, and B (j) is the minimum value among the indices of the plurality of MDCT coefficients constituting the subband j. Indicates the value. W (j) indicates the bandwidth of subband j, and in the following description, the case where all the J subbands have the same bandwidth, that is, the case where W (j) is a constant will be described as an example.

Next, the band selection unit 301 is a band to be quantized (band to be quantized) of a region having the maximum average energy E1 (m), for example, a band composed of subbands j ″ to (j ″ + L−1). The index m_max indicating this region is output to the shape encoding unit 302 and the multiplexing unit 304 as band information. Further, the band selection unit 301 outputs the first layer difference spectrum X1 (k) of the quantization target band to the shape coding unit 302. In the following description, it is assumed that the band index indicating the quantization target band selected by the band selection unit 301 is j ″ to (j ″ + L−1).

The shape encoding unit 302 performs shape quantization for each subband on the first layer difference spectrum X1 (k) corresponding to the band indicated by the band information m_max input from the band selection unit 301. Specifically, the shape encoding unit 302 searches the built-in shape codebook composed of SQ shape code vectors for each of the L subbands, and evaluates the shape scale_q (i) of Equation (6) below. Find the index of the shape code vector that maximizes.

In this equation, SC ⁱ _k indicates a shape code vector constituting the shape code book, i indicates an index of the shape code vector, and k indicates an index of an element of the shape code vector.

The shape encoding unit 302 outputs the shape code vector index S_max that maximizes the evaluation measure Shape_q (i) of the above equation (6) to the multiplexing unit 304 as shape encoding information. The shape encoding unit 302 calculates an ideal gain Gain_i (j) according to the following equation (7), and outputs the calculated ideal gain Gain_i (j) to the gain encoding unit 303.

The gain encoding unit 303 quantizes the ideal gain Gain_i (j) input from the shape encoding unit 302 according to the following equation (8). Here, gain encoding section 303 treats the ideal gain as an L-dimensional vector, searches for a built-in gain codebook composed of GQ gain code vectors, and performs vector quantization.

Here, the index of the gain codebook that minimizes the square error Gain_q (i) of the above equation (8) is denoted as G_min.

The gain encoding unit 303 outputs G_min to the multiplexing unit 304 as gain encoding information.

Multiplexer 304 multiplexes band information m_max input from band selector 301, shape encoded information S_max input from shape encoder 302, and gain encoded information G_min input from gain encoder 303. The obtained bit stream is output to the second layer decoding section 206, the third layer encoding section 208, and the encoded information integration section 209 as second layer encoded information.

FIG. 5 is a block diagram illustrating a main configuration of the second layer decoding unit 206.

In this figure, the second layer decoding unit 206 includes a separation unit 401, a shape decoding unit 402, and a gain decoding unit 403.

Separating section 401 separates band information, shape coding information, and gain coding information from the second layer coding information output from second layer coding section 205, and obtains the obtained band information and shape coding information. The result is output to shape decoding section 402, and the gain encoded information is output to gain decoding section 403.

The shape decoding unit 402 obtains the shape value of the MDCT coefficient corresponding to the quantization target band indicated by the band information input from the separation unit 401 by decoding the shape coding information input from the separation unit 401, The obtained shape value is output to gain decoding section 403. Details of the processing of the shape decoding unit 402 will be described later.

The gain decoding unit 403 uses a built-in gain codebook to dequantize the gain encoded information input from the separating unit 401 to obtain a gain value. Gain decoding section 403 obtains a decoded MDCT coefficient of the quantization target band using the gain value obtained and the shape value input from shape decoding section 402, and uses the obtained decoded MDCT coefficient as the second layer decoded spectrum. The result is output to the adding unit 207. Details of the processing of the gain decoding unit 403 will be described later.

The second layer decoding unit 206 having the above configuration performs the following operation.

Separating section 401 separates band information m_max, shape encoded information S_max, and gain encoded information G_min from the second layer encoded information input from second layer encoding section 205, and provides obtained band information m_max and shape The encoded information S_max is output to the shape decoding unit 402, and the gain encoded information G_min is output to the gain decoding unit 403.

The shape decoding unit 402 incorporates a shape code book similar to the shape code book included in the shape coding unit 302 of the second layer coding unit 205, and uses the shape coding information S_max input from the separation unit 401 as an index. Search for shape code vectors. The shape decoding unit 402 outputs the searched shape code vector to the gain decoding unit 403 as the shape value of the MDCT coefficient in the quantization target band indicated by the band information m_max input from the separation unit 401. Here, the shape code vector searched as a shape value is denoted as Shape_q ′ (k) (k = B (j ″),..., B (j ″ + L) −1).

Gain decoding section 403 incorporates a gain codebook similar to the gain codebook included in gain encoding section 303 of second layer encoding section 205, and dequantizes the gain value according to the following equation (9). Again, the gain value is treated as an L-dimensional vector, and vector inverse quantization is performed. That is, the gain code vector GC _j ^G_min corresponding to the gain encoded information G_min is directly set as the gain value.

Next, the gain decoding unit 403 uses the gain value obtained by inverse quantization of the current frame and the shape value input from the shape decoding unit 402, according to the following equation (10), and the second layer decoded spectrum X2 "(K) calculates the decoded MDCT coefficient. In addition, in the inverse quantization of the decoded MDCT coefficient, when k exists in B (j") to B (j "+1) -1, the gain value is Gain_q '. The value of (j ″) is taken.

The gain decoding unit 403 outputs the second layer decoded spectrum X2 ″ (k) calculated according to the above equation (10) to the adding unit 207.

FIG. 6 is a block diagram showing a main configuration of third layer encoding section 208.

In this figure, the third layer encoding unit 208 includes a band selection unit 301, a shape encoding unit 302, a gain correction coefficient setting unit 601, a gain encoding unit 602, and a multiplexing unit 304. Note that the band selection unit 301 and the shape encoding unit 302 are the same as the components in the second layer encoding unit 205 except that the names of input and output information are different, and therefore the same code The description is omitted.

Band information is input from the band selection unit 301 to the gain correction coefficient setting unit 601. This band information is information of a band selected as an encoding target by the third layer encoding unit 208, and is hereinafter referred to as “third layer band information”.

Also, the second layer encoding information is input from the second layer encoding unit 205 to the gain correction coefficient setting unit 601. This second layer encoded information includes information on the band selected as an encoding target by second layer encoding section 205. Hereinafter, the information on the band selected as the encoding target by the second layer encoding unit 205 is referred to as “second layer band information”.

Gain correction coefficient setting section 601 sets a correction coefficient used when quantizing the gain information for each subband indicated by the third layer band information from the second layer band information and the third layer band information. To do.

Specifically, when the subbands indicated by the second layer band information are not included in the subbands indicated by the third layer band information (that is, the third layer encoding unit 208 performs the second layer encoding unit 205). In the case of encoding a band not selected as an encoding target, a gain correction coefficient γ _j is set as shown in the following equation (11).

Further, when each subband indicated by the third layer band information includes a subband indicated by the second layer band information (that is, the third layer encoding unit 208 encodes the second layer band information by the second layer encoding unit 205). When re-encoding the band selected as the conversion target), the gain correction coefficient γ _j is set as in the following equation (12).

The gain correction coefficient setting unit 601 outputs the set gain correction coefficient γ _j to the gain encoding unit 602.

The ideal gain is input from the shape encoding unit 302 to the gain encoding unit 602. The gain encoding unit 602 receives the gain correction coefficient γ _j from the gain correction coefficient setting unit 601. The gain encoding unit 602 corrects the ideal gain by dividing the ideal gain input from the shape encoding unit 302 by the gain correction coefficient γ _j as shown in Expression (13).

Next, gain encoding section 602 quantizes ideal gain Gain_i ′ (j) corrected using gain correction coefficient γ _j according to equation (13) to obtain gain encoded information.

Specifically, the gain encoding unit 602 uses the ideal gain Gain_i ′ (j) corrected using the gain correction coefficient γ _j according to Equation (13), and uses GQ pieces for each of the L subbands. The built-in gain codebook consisting of the gain code vectors is searched for, and the index of the gain code vector that minimizes the square error Gainq_i (i) in equation (14) is obtained.

In this equation, GC ⁱ _j indicates a gain code vector constituting the gain codebook, i indicates an index of the gain code vector, and j indicates an index of an element of the gain code vector. For example, when the number of subbands constituting the region is 5 (L = 5), j takes a value from 0 to 4. Gain coding section 602 treats L subbands in one region as an L-dimensional vector and performs vector quantization.

The gain encoding unit 602 outputs the index G_min of the gain code vector that minimizes the square error Gainq_i (i) of the above equation (14) to the multiplexing unit 304 as gain encoding information.

In this way, gain correction coefficient setting section 601 includes a case where the subband indicated by the third layer band information does not include the subband indicated by the second layer band information in the lower layer, and a case where it is included. Thus, the gain correction coefficient γ _j for correcting the ideal gain is switched as in Expression (11) or Expression (12).

Then, when the gain information of the quantization target band of the current layer is quantized, the gain encoding unit 602 obtains the gain for the quantization target band quantized in the lower layer with respect to the corresponding element of the gain codebook. Using the ideal gain corrected by the correction coefficient γ _j, a gain code vector that most closely approximates the ideal gain after correction is searched from the gain code book.

As can be seen from Equation (11) and Equation (12), in this embodiment, the subband indicated by the third layer bandwidth information that is the current layer includes the subband indicated by the second layer bandwidth information in the lower layer. The ideal gain Gain_i (j) is corrected so as to increase.

That is, the gain correction coefficient γ _j represents the distribution of gain code vectors in the quantization target band of the current layer, the distribution of gain code vectors in the quantization target band of the lower layer (the gain code vector in the gain codebook). It can be said that the coefficient approaches the size distribution.

As a result, even when performing vector quantization of a plurality of elements having greatly different energies, the magnitude of the energy of each element of the gain code vector can be smoothed. Can be made.

The above is the processing description of the third layer encoding unit 208.

The above is the processing description of the encoding apparatus 101.

FIG. 7 is a block diagram showing a main configuration inside decoding apparatus 103 shown in FIG. As an example, the decoding apparatus 103 is a hierarchical decoding apparatus including three decoding hierarchies (layers). Here, like the encoding apparatus 101, the first layer, the second layer, and the third layer are referred to in order from the lowest bit rate.

The encoded information separation unit 701 receives the encoded information sent from the encoding apparatus 101 via the transmission path 102, separates the encoded information into encoded information of each layer, and performs decoding processing responsible for each decoding process To the output. Specifically, the encoded information separation unit 701 outputs the first layer encoded information included in the encoded information to the first layer decoding unit 702, and the second layer encoded information included in the encoded information. Are output to second layer decoding section 703 and third layer decoding section 704, and the third layer encoded information included in the encoded information is output to third layer decoding section 704.

First layer decoding section 702 decodes the first layer encoded information input from encoded information separating section 701 using, for example, a CELP speech decoding method to generate a first layer decoded signal. The generated first layer decoded signal is output to adding section 707.

Second layer decoding section 703 decodes the second layer encoded information input from encoded information separating section 701, and outputs the obtained second layer decoded spectrum X2 ″ (k) to adding section 705. Since the processing of the layer decoding unit 703 is the same as the processing of the second layer decoding unit 206 described above, description thereof is omitted here.

Third layer decoding section 704 decodes the third layer encoded information input from encoded information separating section 701, and outputs the obtained third layer decoded spectrum X3 ″ (k) to adding section 705. The processing in the layer decoding unit 704 will be described later.

The adder 705 receives the second layer decoded spectrum X2 ″ (k) from the second layer decoder 703. Also, the adder 705 receives the third layer decoded spectrum X3 ″ from the third layer decoder 704. (K) is input. Adder 705 adds input second layer decoded spectrum X2 ″ (k) and third layer decoded spectrum X3 ″ (k), and performs orthogonal transform processing using the added spectrum as first added spectrum X4 ″ (k) To the unit 706.

The orthogonal transform processing unit 706 first initializes a built-in buffer buf ′ (k) to a “0” value according to the following equation (15).

The orthogonal transform processing unit 706 receives the first addition spectrum X4 ″ (k) and obtains the first addition decoded signal y ″ (n) according to the following equation (16).

In this equation, X5 (k) is a vector obtained by combining the first addition spectrum X4 ″ (k) and the buffer buf ′ (k), and is obtained using the following equation (17).

Next, the orthogonal transform processing unit 706 updates the buffer buf ′ (k) according to the following equation (18).

The orthogonal transform processing unit 706 outputs the first addition decoded signal y ″ (n) to the adding unit 707.

The first layer decoded signal is input from the first layer decoding unit 702 to the adding unit 707. Further, the first addition decoded signal is input from the orthogonal transform processing unit 706 to the adding unit 707. Adder 707 adds the input first layer decoded signal and first added decoded signal, and outputs the added signal as an output signal.

FIG. 8 is a block diagram showing the main configuration of the third layer decoding unit 704.

In this figure, the third layer decoding unit 704 includes a separation unit 801, a shape decoding unit 402, a gain correction coefficient setting unit 802, and a gain decoding unit 803. In addition, since the shape decoding part 402 is the same as the structure mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

Separating section 801 separates band information, shape encoded information, and gain encoded information from the third layer encoded information input from encoded information separating section 701, and converts the obtained band information into shape decoding section 402 and gain It outputs to correction coefficient setting section 802, outputs shape coding information to shape decoding section 402, and outputs gain coding information to gain decoding section 803.

The band information is input from the separating unit 801 to the gain correction coefficient setting unit 802. This band information is the third layer band information selected as an encoding target by the third layer encoding unit 208.

Also, the gain correction coefficient setting unit 802 receives the second layer encoded information from the encoded information separation unit 701. The second layer encoded information includes second layer band information selected as an encoding target by the second layer encoding unit 205.

Gain correction coefficient setting section 802 sets a correction coefficient used when quantizing gain information for each subband indicated by the third layer band information from the second layer band information and the third layer band information. To do.

Specifically, when the subbands indicated by the second layer band information are not included in the subbands indicated by the third layer band information (that is, the third layer decoding unit 704 is configured by the second layer decoding unit 703). When decoding a band not selected as a decoding target), the gain correction coefficient γ _j is set as shown in the above equation (11).

In addition, when each subband indicated by the third layer band information includes a subband indicated by the second layer band information (that is, the third layer decoding unit 704 selects the second layer decoding unit 703 as a decoding target). When the band not selected is decoded again), the gain correction coefficient γ _j is set as in the above equation (12).

The gain correction coefficient setting unit 802 outputs the set gain correction coefficient γ _j to the gain decoding unit 803.

The gain decoding unit 803 directly dequantizes the gain encoded information input from the separation unit 801 using a built-in gain codebook to obtain a gain value. Specifically, gain decoding section 803 has a built-in gain codebook similar to gain encoding section 602 of third layer encoding section 208, and calculates gain correction coefficient γ _j according to the following equation (19). The gain value Gain_q ′ is obtained by performing inverse quantization of the gain. Here, gain decoding section 803 treats L subbands in one region as an L-dimensional vector, and performs vector inverse quantization.

Next, gain decoding section 803 uses the gain value obtained by inverse quantization of the current frame and the shape value input from shape decoding section 402 as the third layer decoded spectrum according to the following equation (20). Decode MDCT coefficients are calculated. Here, the calculated decoded MDCT coefficient is denoted as X3 ″ (k). In addition, in the inverse quantization of the MDCT coefficient, when k exists in B (j ″) to B (j ″ +1) −1, The gain value Gain_q ′ (j) takes the value of Gain_q ′ (j ″).

Gain decoding section 803 outputs third layer decoded spectrum X3 ″ (k) calculated according to equation (20) to addition section 705.

The above is the processing description of the third layer decoding unit 704.

The above is the process description of the decryption device 103.

As described above, according to the present embodiment, in coding apparatus 101 that performs hierarchical coding (scalable coding) that selects a band to be coded (band to be quantized) for each layer (layer), lower order Based on the comparison result between the quantization target band of the layer and the quantization target band of the current layer, the third layer encoding unit 208 performs a quantization method for gain information (energy information) of the quantization target band of the current layer. Switch.

That is, when the subband indicated by the third layer band information which is the current layer in third layer encoding section 208 includes the subband indicated by the second layer band information in the lower layer, gain encoding section 602 Quantization is performed after correcting Gain_i (j) to be large. As a result, the energy magnitude of each element of the gain codebook can be smoothed even when vector quantization is performed on a plurality of gain information having greatly different energies. Therefore, it is possible to efficiently vector quantize the gain information of a plurality of subbands consisting of subbands that are selected and quantized in the lower layer and subbands that are not, using the same gain codebook, The quality of the decoded signal can be improved.

In the gain correction coefficient setting unit according to the present embodiment, γ _j = 0.5 is set for the subbands selected in the lower layer, and γ _j = 1.0 is set for the other subbands. However, the present invention is not limited to this, and can be similarly applied to setting values other than those described above.

Also, the setting method of the gain correction coefficient is not limited to the setting method as described above, and may be set by statistical calculation using many input samples.

In the present embodiment, the configuration has been described in which the ideal gain is first divided by the gain correction coefficient to flatten the energy and the value is vector quantized. However, the present invention is not limited to this, and the gain codebook to be searched is described. The same applies to a configuration in which each gain code vector is multiplied by a gain correction coefficient. However, in the configuration described in the present embodiment, the number of calculations using the gain correction coefficient is reduced compared to the above configuration, so that the quality can be improved without significantly increasing the calculation amount.

In the present embodiment, the method has been described in which the gain values of the entire vector are made uniform by increasing the gain value of the subband quantized in the lower layer. However, the present invention is not limited to this. Contrary to the above method, the present invention can be similarly applied to the case where the gain values of the entire vector are made uniform by reducing the gain values of the subbands not quantized in the lower layer.

In the present embodiment, a configuration has been described in which a gain code vector that minimizes a square error is searched for a value obtained by dividing an ideal gain by a gain correction coefficient, and a gain value is encoded. The present invention is not limited to this, and the present invention can be similarly applied to the case where the square error is calculated based on the magnitude of the gain correction coefficient. A specific method will be described below. For example, when the value of the gain correction coefficient is 0.5, the value after dividing by the gain correction coefficient is twice the original gain value. Therefore, the corresponding subband is calculated by multiplying the square error value by 0.5. Thereby, the distance (error) in the distribution before correction by the gain correction coefficient can be calculated, and as a result, the quality of the decoded signal can be improved.

Although the first layer encoding unit in the present embodiment has been described by taking as an example a configuration employing the CELP encoding method, the present invention is not limited to this, and there is no first layer encoding unit. The same applies to cases. The first layer encoding unit can be similarly applied to a configuration in which the frequency component is encoded in the same manner as the second layer encoding unit.

Also, the same applies to the configuration in which the first layer encoding unit does not encode the entire band as in the second layer encoding unit, but partially selects and encodes the band to be encoded. Applicable to. In the case of this configuration, the frequency components of the entire band are not quantized by the first layer encoding unit, so the second layer encoding unit is also described in the present embodiment. A configuration in which a gain component (energy component) quantization method such as a three-layer encoding unit is switched can also be applied. In that case, the same gain correction coefficient may be used in the encoding section of each layer, or different gain correction coefficients may be used in the encoding section of each layer.

In each band, a different gain correction coefficient can be set according to the number of times selected as a quantization target band in the lower layer. The gain correction coefficient in this case can also be statistically calculated and set using many input samples.

It should be noted that the present invention can be applied to the decoding apparatus in the same manner for each configuration corresponding to the configuration of the encoding apparatus.

Further, in the present embodiment, the configuration in which the encoding apparatus includes three encoding layers (three layers) has been described. However, the present invention is not limited to this, and the present invention can be similarly applied to configurations other than three layers. .

Also, in the present embodiment, the configuration in which the first layer encoding unit / decoding unit of the lowest layer employs the CELP encoding / decoding method has been described, but the present invention is not limited to this, and the CELP encoding / decoding method is used. The same applies to the case where there is no layer that employs the encoding / decoding method. For example, an adder that performs addition and subtraction on the time axis on the encoding device and the decoding device is not required for a configuration that is a layer of the frequency transform encoding / decoding method.

Further, in the present embodiment, the configuration has been described in which, in the encoding device, the differential signal between the first layer decoded signal and the input signal is calculated and then orthogonally transformed to calculate the differential spectrum. This is not limited to this, and the same applies to a configuration in which an orthogonal transform process is first performed on the input signal and the first layer decoded signal, and the difference spectrum is calculated after calculating the input spectrum and the first layer decoded spectrum, respectively. Applicable to.

In addition, the decoding apparatus according to the present embodiment performs processing using the encoded information transmitted from the encoding apparatus according to each of the above embodiments, but the present invention is not limited to this, and necessary parameters and As long as the encoded information includes data, the process can be performed even if it is not necessarily the encoded information from the encoding device in each of the above embodiments.

The present invention can also be applied to a case where a signal processing program is recorded and written on a machine-readable recording medium such as a memory, a disk, a tape, a CD, or a DVD, and the operation is performed. Actions and effects similar to those of the form can be obtained.

Further, although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be realized by software.

Further, each functional block used in the description of the present embodiment is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Although referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable / processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of advances in semiconductor technology or other derived technology, it is naturally also possible to integrate functional blocks using this technology. Biotechnology can be applied.

The disclosure of the specification, drawings and abstract contained in Japanese Patent Application No. 2009-237684, filed on October 14, 2009, is incorporated herein by reference.

INDUSTRIAL APPLICABILITY The encoding apparatus, decoding apparatus and these methods according to the present invention can improve the quality of a decoded signal in a configuration in which a quantization target band is hierarchically selected and encoded / decoded. It can be applied to mobile communication systems.

DESCRIPTION OF SYMBOLS 101 Coding apparatus 102 Transmission path 103 Decoding apparatus 201 1st layer encoding part 202,702 1st layer decoding part 203,207,705,707 Adder 204,706 Orthogonal transformation process part 205 2nd

layer encoding part

206, 703 Second layer decoding unit 208 Third layer encoding unit 209 Encoding information integration unit 301 Band selection unit 302

Shape encoding unit

303, 602 Gain encoding unit 304

Multiplexing unit

401, 801 Separation unit 402

Shape decoding unit

403, 803

Gain decoding unit

601, 802 Gain correction coefficient setting unit 701 Encoding information separation unit 704 Third layer decoding unit

Claims

An encoding device having at least two encoding layers,
A first input signal in a frequency domain is input, a first quantization target band of the first input signal is selected from a plurality of subbands obtained by dividing the frequency domain, and the first quantization target band of the first quantization target band is selected. Encoding one input signal to generate first encoded information including first band information of the first quantization target band, and generating a first decoded signal using the first encoded information, First layer encoding means for generating a second input signal using the first input signal and the first decoded signal;
The second input signal and the first encoded information are input, a second quantization target band of the second input signal is selected from the plurality of subbands to obtain second band information, and A gain of the second input signal in the second quantization target band is obtained, the second input signal in the second quantization target band is encoded using the first encoding information, and the second band information is obtained. And second layer encoding means for generating second encoded information including gain encoded information obtained by encoding the gain,
An encoding device comprising:
The second layer encoding means includes
The second quantization target band of the second input signal is selected from the plurality of subbands to generate the second band information, and the second input signal of the second quantization target band is output Band selection means to perform,
Shape / gain encoding means for encoding shape and gain of the second input signal in the second quantization target band to generate shape encoded information and gain encoded information;
The encoding device according to claim 1, comprising:
The second layer encoding means includes
A coefficient for setting a gain correction coefficient for correcting the size of the code vector of the first quantization target band among the code vectors stored in the codebook used for encoding the gain using the first encoding information Further comprising setting means,
The shape / gain encoding means includes:
Encoding the gain using the codebook in which the code vector of the first quantization target band is corrected using the gain correction coefficient;
The encoding device according to claim 2.
The coefficient setting means includes
The gain correction coefficient is set so that the distribution of the code vector size of the second quantization target band in the codebook approaches the distribution of the gain size of the second quantization target band,
The encoding device according to claim 3.
The second layer encoding means includes
Comparison result between the first quantization target band obtained using the first band information included in the first encoded information and the second quantization target band obtained using the second band information Further comprising a selection means for selecting the gain quantization method using
The shape / gain encoding means includes:
Encoding the gain using the quantization method selected by the selection means;
The encoding device according to claim 2.
A communication terminal device comprising the encoding device according to claim 1.
A base station apparatus comprising the encoding apparatus according to claim 1.
A decoding device that receives and decodes information generated in an encoding device having at least two encoding layers,
First band information generated by selecting the first quantization target band of the first layer from among a plurality of subbands obtained by dividing the frequency domain, obtained by encoding the first layer of the encoding device And the second encoding of the second layer out of the plurality of subbands obtained by encoding the second layer of the encoding device using the first encoding information. Receiving means comprising: the second encoded information including second band information generated by selecting a quantization target band; and
The first encoded information obtained from the information is input, and a first decoded signal is generated for the first quantization target band set based on the first band information included in the first encoded information. First layer decoding means;
The first encoded information and the second encoded information obtained from the information are input, and the second quantization target band set based on the second band information included in the second encoded information Second layer decoding means for generating a second decoded signal by performing correction on the signal using the first encoded information and the second encoded information;
A decoding device comprising:
The first layer decoding means includes
First shape decoding means for determining the shape of the first decoded signal for the first quantization target band using the first shape encoded information and the first band information included in the first encoded information;
The gain of the first decoded signal is obtained using first gain encoded information included in the first encoded information, and the shape of the first decoded signal with respect to the first quantization target band and the first decoded signal First gain decoding means for generating the first decoded signal using a gain;
The decoding device according to claim 8, comprising:
The second layer decoding means includes
Second shape decoding means for determining the shape of the second decoded signal for the second quantization target band using the second shape encoded information and the second band information included in the second encoded information;
The gain of the second decoded signal is obtained using second gain encoded information included in the second encoded information, and the first band information and the second encoded information included in the first encoded information are obtained. A correction gain of the second decoded signal is generated by correcting the gain of the second decoded signal using the included second band information, and the shape of the second decoded signal with respect to the second quantization target band and the second Second gain decoding means for generating the second decoded signal using a correction gain of two decoded signals;
The decoding device according to claim 8, comprising:
A communication terminal device comprising the decoding device according to claim 8.
A base station apparatus comprising the decoding apparatus according to claim 8.
An encoding method for encoding with at least two encoding layers,
A first input signal in a frequency domain is input, a first quantization target band of the first input signal is selected from a plurality of subbands obtained by dividing the frequency domain, and the first quantization target band of the first quantization target band is selected. Encoding one input signal to generate first encoded information including first band information of the first quantization target band, and generating a first decoded signal using the first encoded information, A first layer encoding step of generating a second input signal using the first input signal and the first decoded signal;
The second input signal and the first encoded information are input, a second quantization target band of the second input signal is selected from the plurality of subbands to obtain second band information, and A gain of the second input signal in the second quantization target band is obtained, the second input signal in the second quantization target band is encoded using the first encoding information, and the second band information is obtained. And a second layer encoding step for generating second encoded information including gain encoded information obtained by encoding the gain,
An encoding method comprising:
A decoding method for receiving and decoding information generated in an encoding device having at least two encoding layers,
First band information generated by selecting the first quantization target band of the first layer from among a plurality of subbands obtained by dividing the frequency domain, obtained by encoding the first layer of the encoding device And the second encoding of the second layer out of the plurality of subbands obtained by encoding the second layer of the encoding device using the first encoding information. Receiving the information comprising: the second encoded information including second band information generated by selecting a quantization target band; and
The first encoded information obtained from the information is input, and a first decoded signal is generated for the first quantization target band set based on the first band information included in the first encoded information. A first layer decoding step;
The first encoded information and the second encoded information obtained from the information are input, and the second quantization target band set based on the second band information included in the second encoded information A second layer decoding step of generating a second decoded signal by performing correction on the signal using the first encoded information and the second encoded information;
A decoding method comprising: